In an existing pixel circuit, a drive TFT (Thin Film Transistor) is turned on by a data voltage to generate a drive current acting on an OLED (Organic Light-Emitting Diode), thereby driving the OLED to emit light. Due to uncontrollable factors in processes and uncontrollable factors in practical manufacture, characteristics of drive TFTs are not all the same, and may even be quite different. As such, drive currents generated by drive TFTs under a same data voltage may not be the same, and may even be quite different, such that brightness of OLEDs is not uniform.
In the prior art, in order to address this problem, the data voltage is compensated, so that the drive current generated by the drive TFT can have a desired value. In the process of the compensation, a current signal needs to be converted into a voltage signal. However, effect of the compensation is affected by loss of conversion accuracy.